Abstract: A cylindrical battery includes a housing having an accommodating space; and a negative electrode sheet, a first separator, a positive electrode sheet, and a second separator that are wound multiple turns forming an electrode core. The housing is co-axial with the electrode core that is disposed in the accommodating space. The positive electrode sheet includes a positive electrode material layer and a positive electrode foil layer. The negative electrode sheet includes a negative electrode material layer and a negative electrode foil layer. Some of the wound turns of the positive electrode foil layer extends toward an end of the housing to form a positive electrode tab. Some of the wound turns of the negative electrode foil layer extends toward another end of the housing to form the negative electrode tab.

Abstract: A battery core and a battery are provided. The battery core includes a plate, a separator, a tab, and an insulating support portion. The tab is connected with the plate. The insulating support portion is arranged on an end of the plate and supports the tab. The tab extends through the insulating support portion and extends outward.

Abstract: A battery case is provided, including a plurality of side plates. A first side plate has the largest area among the plurality of side plates, and at least one first side plate includes a first portion and a second portion. The first portion is a curved surface concave toward inside of the battery case. A three-dimensional coordinate system is established in a first direction, a second direction, and a third direction, and the second direction is perpendicular to the first side plate. A curvature of the first portion is less than a curvature of an ellipsoid, the curvature of the ellipsoid is obtained from an ellipsoid function, and the ellipsoid function is: ((x?a)/i)2+((y?b)/j)2+((z?c)/k)2=1, where, a, b, c, i, j, and k are determined according to coordinates of at least four points that are different from each other, and x, y, and z are coordinates of the three directions of the ellipsoid function.

Abstract: A cell array, including a plurality of cells arranged in sequence is provided. Each of the plurality of cells includes a housing and an electrode core. The electrode core includes an electrode plate. The electrode plate includes a current collector and a coating layer arranged on the current collector. The cell array satisfies the following formula 1: (1?JRw)+(SRw?1)=10%?15%. JRw is an expansion space for the electrode core inside each of the plurality of cells in a first direction, SRw is an expansion space outside the plurality of cells in the first direction, and a thickness direction of each of the plurality of cells is defined as the first direction. JRw=Pw/(Cellw?Kw?Cw). SRw=(Mw?MNw)/(Celln×Cellw).

Abstract: A battery, a battery module, a battery pack, and an electric vehicle are provided. The battery includes a metal shell and a plurality of electrode core assemblies sealed in the metal shell and arranged in sequence. The electrode core assemblies are connected in series. Each of the electrode core assemblies includes at least one electrode core. The electrode core assemblies are sealed in a packaging film. An air pressure between the metal shell and the packaging film is lower than an air pressure outside the metal shell. An air pressure inside the packaging film is lower than the air pressure between the metal shell and the packaging film.

Abstract: An electrode assembly for a lithium-ion secondary battery and a preparation method thereof, and a lithium-ion secondary battery are disclosed. The electrode assembly comprises an electrode and an electrode post, where an electrode tab is extended from the electrode; a welding connection portion is formed by welding between the electrode tab and the electrode post; the welding connection portion has a bulge welding defect; the surface of the welding connection portion is covered with a polymer protective layer, and the thickness of the polymer protective layer is greater than or equal to the thickness of the bulge welding defect; and the bulge welding defect is embedded in the polymer protective layer.